1. Field of the Invention
The present invention is related to positioning systems, and more particularly, to tie-in devices for the correlation of two or more coordinate systems to facilitate positioning of a component.
2. Description of Related Art
Assembly of large structures, such as aircraft, requires the use of large-scale measurement systems to ensure proper assembly of the structures. Components of these large structures are typically assembled using large steel holding fixtures that are by necessity rigid and fixed to the factory floor. The fixtures support the components and provide limited movement capability to slide the components together for assembly. The fixtures require periodic measurement, or surveying, to ensure that the fixture is in proper alignment for the specialized assembly procedure. The fixtures typically do not allow for flexibility in the assembly process. For example, each fixture typically requires a specific design for the component and assembly procedure it facilitates. Accordingly, changes to the component or assembly procedure can be expensive. Furthermore, factory floor space is occupied by fixtures that are not suited for other activities.
Therefore, it is desirable to provide adaptable fixtures that can be used for various components and assembly procedures. One consideration in the design of fixtures is the positioning of various components relative to one another during the assembly procedure. The components must be accurately aligned and positioned during assembly in order for the assembled structure to have the proper structural properties and optimal performance characteristics.
Presently, many existing measurement technologies are used independently during the assembly of such components to ensure proper or optimal assembly. Measurements are typically made relative to predetermined points on the fixtures, and those measurements are used to determine the position or alignment of the component supported by the fixture. These determinations are based on various assumptions, such as assumptions regarding the position of the component relative to the fixture; therefore, the accuracy of such determinations is limited. In addition, these measurements are taken well in advance of the actual assembly, thus these measurement techniques may not provide real-time information during assembly to ensure proper and/or optimal assembly of the components.
Present measurement systems, also called locating devices, also do not provide techniques to accurately correlate the measurement data taken with multiple measurement systems in real-time. These measurement systems take measurements in independent coordinate systems. Measurement systems may transfer measurement data amongst the various systems, but the process is typically done by file transfer and can be very time consuming, considering the feedback and control systems for large component positioning systems require nearly instantaneous measurements for adequate performance.
Therefore, a need for correlating two or more coordinate systems of independent measurement systems exists. This ability to correlate at least two different coordinate systems would allow multiple measurement systems to provide measurement data in real-time during the assembly of large components to ensure proper and/or optimal assembly of the components.